Audiences these days are more demanding of speakers. I don't believe it's because attention spans have dropped, even though there is much more short-form information around. I believe it's because speakers are now in a battle for attention with other sources of information. Most audience members will check their mobile phones at some point. Many will be using web-connected iPads or other tablets to communicate with people outside. For some, your speech may be background noise.
That doesn't mean that your audience isn't paying attention to your wisdom. It does mean that you have to be more interesting than whatever is happening on their iPhones. If you deliver a piece of information, you need to be aware that it can be checked in seconds, and you may be challenged. If you tell a story, make it so engaging that people have to give it their full attention. If you use slides, make the information so obvious that people can absorb it in a few seconds.
Some speakers bemoan the fact that control has passed from them to their audience. They're missing the point. The audience was always in charge, and the speaker is there to serve. These days, the level of service has to be even higher.